Electricity generation - what are the options?

Electricity is vital to modern life. It powers our lights and appliances at home. It powers many industry processes. It is used to power trains and to charge electric vehicles.

Globally, electricity use is rising rapidly as new major economies develop in places such as China and India. This need for electricity drives a growing demand for electricity generation, with thousands of new power plants needed across the world over the coming decades.

Every form of electricity generation has its strengths and weakness and future electricity generation will need a range of options, although they must be low carbon if greenhouse gas emissions are to be reduced. Nuclear generation provides reliable supplies of electricity, with very low carbon emissions and relatively small amounts of waste that can be safely stored and eventually disposed of.

For many decades almost all the electricity consumed in the world has been generated from three different forms of power plant - fossil, hydro and nuclear. Renewables currently generate a relatively small share of the world's electricity, although that share is growing fast.

Fossil

Fossil fuel power plants burn carbon fuels such coal, oil or gas to generate steam that drives large turbines that produce electricity. These plants can generate electricity reliably over long periods of time. However, by burning carbon fuels they produce large amounts carbon dioxide, which causes climate change. They can also produce other pollutants, such as sulphurous oxides, which cause acid rain.

The Cottam power plant in the UK has coal and gas burners on the same site (EDF Energy)

Fossil fuel plants require huge quantities of coal, oil or gas. These fuels may need to be transported over long distances. The price of fuels can rise sharply at times of shortage, leading to unstable generation costs.

Large hydro

Large hydro power plants generate electricity by storing water in vast reservoirs behind massive dams. Water from the dams flows through turbines to generate electricity, and then goes on to flow through rivers below the dam.

Hydro dams can generate large amounts of electricity. However, dry periods can drain the reservoirs. The flooding of reservoirs behind dams and slowing of the flow of the river below the dam can have a serious impact on the ecology around the dam. The number of sites suitable for new dams is limited.

Nuclear

Nuclear power plants use the heat produced by nuclear fission to generate steam that drives turbines, like in fossil fuel plants. However, no greenhouse gases are produced in this fission process, and only small amounts are produced across the whole fuel cycle.

Point Beach nuclear power plant in the USA (NextEra)

Nuclear fuel can be used in a reactor for several years. The used fuel that remains after this time must be stored and then either recycled to make new fuel or carefully disposed of. However, because the amount of fuel used to generate electricity is so much less than that used in fossil fuel plants it is much more practical to do this with used nuclear fuel than with the wastes and emissions from fossil fuels.

Nuclear power plants can run for many months without interruption, providing reliable and predictable supplies of electricity.

Nuclear power plants can generate electricity "24/7" for many months at a time, without interruption. Nuclear generation is one of the safest and least environmentally damaging forms of electricity generation

Renewables

Renewables such as wind, solar and small scale hydro produce electricity with no greenhouse gas emissions at the point of generation and very low amounts of greenhouse gas emissions across their entire lifecycle.

The cost of electricity generation from many renewables tends to be higher than other forms of generation, often requiring subsidies to compete with other forms of generation, although these costs are coming down.

Wind turbines in Norway (IEV-Ltd)

Many renewables do not produce electricity predictably or consistently. Electricity generation from wind turbines varies with the wind speed, and if that wind is too weak or too strong no electricity is produced at all. The output of solar panels is reliant on the strength of the sunshine, which depends on the time of day and the amount of cloud cover. This means that renewables have to be backed up by other forms of electricity generation, often fossil fuel generation with their resultant greenhouse gas emissions.